As a liquid crystal display element, there is a liquid crystal display element wherein alignment (initial alignment) of liquid crystal molecules in a liquid crystal layer is substantially vertical to the substrate surface when no voltage is applied. Such a liquid crystal display element is called a VA (vertical alignment) type liquid crystal display element. In the VA-type liquid crystal display element, liquid crystal having a negative dielectric anisotropy is used. And, by applying a voltage to the liquid crystal layer, liquid crystals (liquid crystal molecules) are orientated towards horizontal to the substrate surface (e.g. Patent Document 1). With the VA-type liquid crystal display element, it is possible to increase the responsivity and to realize a display with a high contrast, as compared with a TN (twisted nematic) type liquid crystal display element or a STN (super twisted nematic) type liquid crystal display element (e.g. Patent Document 2).
In a case where alignment of liquid crystals in the voltage-off state, is completely vertical to the substrate, it is not possible to prescribe the tilting direction of liquid crystals when a voltage is applied. Consequently, the alignment of liquid crystals tends to be non-uniform, and the display quality deteriorates. Therefore, it is necessary to prescribe the tilting direction of liquid crystals by imparting a pretilt by some methods or by adjusting the shapes of electrodes. The method for prescribing a tilting direction of liquid crystals by imparting a pretilt or by adjusting the shapes of electrodes, may, for example, be an oblique electric field method wherein the electric field direction by an applied voltage is made oblique to the substrate surface, a rib method wherein electrodes, etc. are provided with a rib structure, or an oblique vapor deposition method wherein silicon oxide (SiO2) is obliquely vapor-deposited on a substrate. Further, it is also possible to prescribe the alignment direction of liquid crystals by applying rubbing treatment to a vertical alignment type alignment film.
Further, as a method for prescribing the alignment direction of liquid crystals, a method of forming slits in an electrode is known. For example, Patent Document 3 discloses a liquid crystal display device wherein a plurality of openings are regularly formed in an electrode to define sub-pixel regions by such openings, so that liquid crystal molecules in such sub-pixel regions are axially symmetrically aligned. In the liquid crystal display device disclosed in Patent Document 3, the sub-pixel regions are defined so that at least one of corners and sides of a polygonal shape have such openings. Further, domain division to let a plurality of alignment directions co-exist by a method of forming slits in an electrode has also been proposed.